Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
theatre [ˈθɪətər] (US) theater n теа́тр; (also: lecture theatre) лекцио́нный зал; (MED) (also: operating theatre) операцио́нная f adj
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.